Level compensating troughing roller assembly for belt conveyors



i Dec. 25, 1962 R. F. LO PRESTI 3,

LEVEL COMPENSATING TROUGHING ROLLER ASSEMBLY FOR BELT CONVEYORS Filed Sept. 9, 1958 3 Sheets-Sheet 1 w 1 in INVENTOR. Roy F LoPresti TTORNEY Dec. 25, 1962 I R. F. LO PRESTI 3,070,217

LEVEL COMPENSATING TROUGHING ROLLER ASSEMBLY FOR BELT CONVEYORS Filed Sept. 9, 1958 3 Sheets-Sheet 2 INVENTOR.

Roy E k Lo Presui ATTORNEY Dec. 25, 1962 3,070,217

LEVEL COMPENSATING TROUGHING ROLLER ASSEMBLY FOR BELT CONVEYORS Filed Sept. 9, 1958 R. LO PRESTI 3 Sheets-Sheet 3 Fig. 6

' INVENTOR. Roy F LoPresu ATTORNEY United States Patent ()fiice 3,070,217 LEVEL COMPENSATING TROUGHIN G ROLLER ASSEMBLY FOR BELT CONVEYORS Roy F. Lo Presti, Chicago, Ill., assignor to Goodman Manufacturing Company, Chicago, 111., a corporation of Illinois Filed Sept. 9, 1958, Ser. No. 760,013 3 Claims. (Cl. 108-192) This invention relates to conveyors and is particularly directed to means for maintaining the primary training rollers of roller assemblies in a flexible strand conveyor at a substantially constant level to thereby maintain the belt centered under all load conditions.

Flexible strand conveyors of the type illustrated in the Craggs et al. Patent No. 2,773,257 are coming into increasingly widespread use due to their ruggedness, ease of assembly and low costs of installation, maintenance and initial investment.

These conveyors usually include a plurality of spaced supporting stands adapted to engage the ground or other solid support structure, and a pair of flexible strands strung between adjacent stands. A plurality of roller assemblies which may vary considerably in design and construction are usually suspended from the flexible strands. Two widely used constructions are the cradled type and the free swinging type. In the cradled assembly, a plurality of rollers, usually three, are pivotally linked together and connected at the outer ends to a rigid metal concave frame or cradle which surrounds them and in turn is connected to the flexible strands. In the free swinging type, the cradle is eliminated and the terminal ends of the rollers are connected directly to the flexible strands. By proper transverse spacing of the stands, the flexible strands may be substantially uniformly spaced throughout the entire length of the conveyor.

The flexible strands, which may be wire ropes for example, may be non-movably secured to the support stands or merely supported thereon. In either case, a catenary sag will occur between adjacent stands and this sag may be accentuated when roller assemblies are suspended across the strands. There may also be an inward movement of the strands, due primarily to the weight of the roller assemblies, and the net result is that those assemblies furthest from the ground engaging support points, that is, those near the midpoint between consecutive stands, tend to settle to a level lower than assemblies adjacent the stands. Occasionally, the settling of the strands between adjacent support points affects the training of the belt under no load conditions, most particularly when, due to poor installation or other causes beyond the control of .the manufacturer, proper strand tension is not maintained. If, for example, the higher roller assemblies should be uniformly or generally canted in one direction and the lower assemblies in another, so that the net training eflect of each set of assemblies is in different directions, the belt may tend to become detrained in the direction in which the higher assemblies are canted because the belt makes contact only with these assemblies. This same belt under load conditions may ride perfectly straight along the assemblies because the opposing training tendencies of the assemblies cancel out since the belt presses firmly against each of them. The real problem therefore arises when the belt is run empty.

Accordingly, the primary object of this invention is the provision of means for maintaining the training rollers of a flexible strand conveyor at approximately a constant level.

Another object is the provision of a roller assembly including a double rope engaging attachment whereby the level of the roller assembly may be varied by utilizing difierent portions of the attachment depending on the position of the assembly with respect to the stands.

Another object is the provision of a level ride rope sidefname conveyor having a variable effective length flexible troughing idler assembly which may be easily adjusted to raise and lower the level of the assembly.

A further object is the provision of a double rope engaging attachment having 'a pair of grooves or recesses rigidly secured to one another, each of which may engage a flexible strand to thereby vary the height of a flexible roller assembly.

Another object is the provision of means for raising the lower roller assemblies of a flexible strand conveyor without substantially increasing the width of the conveyor.

Another object is the provision of means for maintaining the belt of a flexible strand conveyor centered under all load conditions when the roller assemblies are canted in divergent directions.

Other objects will become apparent throughout the course of the following specification and claims.

The invention is illustrated more or less diagrammatically in the following figures wherein:

FIGURE 1 is a side View of a portion of the belt supporting structure of a flexible strand conveyor incorporating one embodiment of the present invention;

FIGURE 2 is a plan view of FIGURE 1;

FIGURE 3 is a diagrammatic double sectional view taken along the lines 33 of FIGURE 2;

FIGURE 4 is a fragmentary enlarged sectional view of FIGURE 2 taken along the line 4-4 of FIGURE 2;

FIGURE 5 is a View similar to FIGURE 4 showing an alternate form of the present invention; and

FIGURE 6 is a view similar to FIGURE 3 showing how the embodiment of FIGURE 5 maintains the rollers of adjacent assemblies at constant positions.

Referring now specifically to FIGURE 1, the belt sup porting structure of a flexible strand type conveyor thereshown includes a support stand 1 having a base 2 adapted to rest upon the ground 3, or other substantially rigid support structure, and a return roller assembly 4. The exact details of the stands may vary widely. Flexible strand receiving members 5 are shown connected to the top of the support stands 1 and receive flexible strands 6 and 7. Although only one support stand has been shown for purposes of clarity, it will be understood that these stands may be regularly spaced at convenient intervals. Twenty feet is an interval commonly used in the coal mining industry for example.

A plurality of free swinging roller assemblies suitably spaced between adjacent support stands are indicated generally at A and B. Roller assembly A includes a primary load carrying roller 10 flanked by end or wing rollers 11 and 12 flexibly connected, as by pivots, thereto. The wing rollers are secured to rope engaging attachments 30 and 31 which will be further described hereinafter. Roller assemblies B are similar to roller assembly A, and like parts are indicated by like reference numerals with a prime. These structurally identical assemblies are separately identified to indicate different positions with respect to the ground. For convenience, roller assemblies A and B will be designated upper and lower assemblies respectively.

Further downstream in the direction of travel of the arrow of FIGURE 2 is a spreader bar indicated generally at 20. The details of the spreader bar may vary widely but in this instance it is shown as comprising an elongated concave body having a generally centrally dished portion 21 and end portions 22 and 23. Attaching means for connecting the spreader bar to the flexible strands 6 and 7 are indicated generally at 24 and 25'. The distance between the flexible strands at the attaching means is sub stantially equal to the distance between the support stands Patented Dec. 25, 1962 1, but due to the catenary sag of the strands, the attaching means are at a lower level. The spreader bars maintain substantially uniform spacing of the flexible strands and eliminate the need for additional support stands which are more expensive than the spreaders. The spreader bars do not, however, counteract the catenary sag of the flexible strands but to the contrary, accentuate it, because they impose additional weight upon the strands.

Referring now to FIGURE 4, a detailed enlargement of the means for connecting the roller assemblies to the flexible strands is thereshown. Wing roller 11 rotates about a dead shaft 13 projecting slightly beyond the outer edge of the roller. A double rope engaging attachment 31 is non-rotatably connected to the shaft 13 by a pair of links 14 and 15. Pivot pins 16 and 17 secure the links to the shaft 13 and elongated leg 32 of the double rope engaging attachment respectively. Suitable spacer washers 18 may be used to maintain the legs 14 and parallel.

The double rope engaging attachment includes a pair of generally 'U-shaped members forming grooves 33 and 34 having depending legs 35, 36 and 37, 32 respectively. Leg 36 of the upper, outer U-shaped member may be suitably secured to the exterior of the lower, inner member by welding or other suitable means. Outer depending legs. 35 and 37 may be suitably apertured to receive suitable means, such as the eye bolt 38, for clamping the attachment to the strand 7. Internal grooves 33 and 34 may have an inner radius of curvature substantially equal to the radius of the flexible strand. The center of curvature of groove 34 is downwardly and inwardly offset with respect to the center of curvature of groove 33 no matter which groove receives the flexible strand.

Referring now to FIGURE 5, a modification of the invention is shown. The upper member forms a groove 43 and includes a first elongated depending leg 42 adapted for connection to shaft 13 by the pivot and link structure of FIGURE 4, and a second depending leg 45. Leg 45 in turn is welded or othewise suitably connected to the lower member which includes depending legs 46 and 47 forming groove 44. In this embodiment the grooves are in effect, stacked one upon the other so that when a flexible strand 7 is received within one of them, the centers of curvature of each groove will lie approximately on a vertical line. Clamping means, such as eye bolt 38, prevent movement of the attachment member along the strand to thereby maintain the roller assembly in any desired position.

The use and operation of the invention is as follows:

In flexible strand conveyors, and especially in those utilizing spacer bars having a width substantially equal to the distance between the suspension points of the flexible strands at the support stands, the problem of belt training may increase when running the conveyor under no load conditions. Due to the catenary sag of the flexible strands between adjacent support stands, the roller assemblies adjacent the stands may be the only assemblies in supporting contact with the belt. If the upper assemblies adjacent the stands are canted with respect to the direction of belt travel, the belt will have a tendency to become detrained in the direction of cant. This same belt may run perfectly centered down the roller assemblies under load conditions because the lower assemblies might be canted in a direction opposite that of the upper assemblies and the detraining tendencies would cancel out.

The double rope engaging attachment structures of FIGURE 4 maintains the belt centered without increasing the width of the conveyor. By placing the flexible strand 7 in the upper, outer grooved member 33 of upper roller assembly A and in the lower, inner grooved member 34 of roller assembly B, the center roller 10' of lower assembly B is brought up substantially to the level of the center roller 10 of assembly A.

The resultant positions of the roller assemblies are illustrated in FIGURE 3. The lower roller assembly has been straightened out an amount substantially equal to the offset between the centers of the radii of curvature of the internal grooves of the grooved members. Actually there would be a slightly greater inward bowing of the flexible strands at the lower assembly than at the upper assembly, but for all practical purposes and for purposes ,of illustration, it can be assumed that the upward movement of the center roller 10 is due substantially entirely to the straightening of the lower roller assembly. This additional inward bowing ensures that the overall width of the conveyor remains constant.

Another important advantage of the double rope engaging attachment 31 is the maintenance of better contact between the belt and lower assembly B. A flexible conveyor belt will not contact the rollers throughout its width due to the inherent stiffness of the belt, and a slight bridging occurs over the points of connection between rollers. By maintaining the center rollers at the same height and the wing rollers 11, 12" at a lower position, the included angle between the rollers of lower assembly B is decreased and the bridging effect is reduced.

An increased centering effect is similarly obtained with the structure of FIGURE 5 as illustrated in FIGURE 6 wherein the centers of the grooves lie substantially on a vertical line. Rope engaging attachment 41 of the upper roller assembly A receives the flexible strand 7 in the upper groove 43 and the attachment 41 of lower assembly B receives the flexible strand in the lower groove 44. In this embodiment the roller assemblies will have the same troughing contour, and the grooved attachments tend to bodily raise the entire lower roller assembly so that a projection of the lower assembly will fall squarely upon a projection of the upper assembly.

In each modification of the invention, the double groove arrangement makes the roller assembly adjustable transversely to the bed of the conveyor so that the groove which receives the flexible strand will depend upon the distance of the roller from the support structure.

Although a preferred and modified embodiment of the invention has been shown and described, it will be understood that the invention is not limited to the disclosed structure which is intended to be illustrative only. Accordingly, the breadth of the invention should be restricted only by the scope of the following appended claims.

I claim:

1. In combination in a flexible belt conveyor,

a pair of flexible sideframes trained along a conveying course such as a mine haulageway,

supporting structures located at intervals along the conveying course for maintaining the sideframes generally parallel and generally coplanar one to another at a plurality of pairs of generally oppositely located support points along the flexible sideframes,

portions of said flexible sideframes between adjacent supporting structures lying at different elevations with respect to a reference plane passing through adjacent pairs of generally oppositely located support points,

a plurality of troughing roller assemblies suspended from the flexible sideframes between adjacent supporting structures, and

means for maintaining the center roller of a first troughing roller assembly in substantially the same plane as the center roller of a second roller assembly,

said first troughing roller assembly being located at a portion of the sideframes which is at a ditferent elevation than the second troughing roller assembly,

said means comprising two pairs of attachments, one pair for each of the first and second troughing roller assemblies, for connecting the assemblies by their ends to the flexible sideframes, each attachment including, in combination,

a pair of grooved members, each grooved member having a groove of a size suflicient to receive therein an associated. sideframe,

each pair of grooved members being offset with respect to one another and rigidly interconnected one to another,

connecting means rigidly secured to one of the grooved members in each attachment and extending toward an associated troughing roller assembly,

the pair of attachments connected to the first troughing roller assembly receiving the flexible sideframes in a first set of grooves,

the pair of attachments connected to the second trough ing roller assembly receiving the flexible sideframes in a second, offset set of grooves,

whereby the center rollers are maintained in substantially the same plane from the first to the second troughing roller assembly,

and clamping means for forcing the sideframes into snug engagement with the grooves to thereby prevent the grooved members from slipping 01f the sideframes as the troughing roller assemblies bounce up and down under varying load conditions.

2. The flexible belt conveyor of claim 1 further characterized in that the grooved members which comprise each pair of rigidly interconnected grooved members are oflset from one another in a substantially horizonta direction.

3. The flexible belt conveyor of claim 1 further characterized in that the grooved members which comprise each pair of rigidly interconnected grooved members are ofiset from one another in a substantially vertical direction.

References Cited in the file of this patent UNITED STATES PATENTS 546,462 Beaton Sept. 17, 1895 1,276,011 Baxter Aug. 20, 1918 1,379,620 Fisher May 31, 1921 2,312,610 Weiss et al. Mar. 2, 1943 2,629,575 Loyot et al. Feb. 24, 1953 2,773,257 Craggs et al. Dec. 4, 1956 2,922,512 Lo Presti Jan. 26, 1960 FOREIGN PATENTS 669,534 Germany Dec. 29, 1938 690,465 Germany Apr. 26, 1940 

